What is the 12-hour clock?
The 12-hour clock is most commonly represented on an analog clock with the numbers 1-12; when shown on a digital clock, it is usually accompanied by a.m. (‘ante meridiem’ – Latin for ‘before midday’) or p.m. (‘post meridiem’ – Latin for ‘after midday’).
What is the 24-hour clock?
The 24-hour clock is more often shown on digital clocks and is written in a 4-digit form, with the first two digits representing the hour and the last two representing the minutes.
There is no need for a.m. or p.m. as each time represents each hour in a 24-hour day. For example, 03:00 = 3rd hour of the day, or 3 am; 14:00 = 14th hour of the day or 2pm; 18:30 = 30 minutes past the 18th hour of the day, or 6:30pm.
How to convert from a 12-hour clock to a 24-hour clock?
To convert from a 12-hour clock to a 24-hour clock, children may be taught to add 12 to the hours after midday, e.g. 3pm becomes 15:00 because 3 + 12 = 15.
When will my child learn about the 12-hour and 24-hour clock in elementary school?
12-hour and 24-hour clock in 1st – 4th grades.
1st grade students will learn to tell the time to the hour and half past the hour using analog and digital clocks.
Children’s learning of time is continued into second grade, where they will tell and write the time from analog and digital clocks, to the nearest 5 minutes, using a.m. and p.m.
By the time your child is in 3rd grade, they are expected to tell and write time to the nearest minute and measure time intervals in minutes. They will learn to represent intervals of time by using number lines. This continues into 4th grade.
There are no specific objectives about time in past 4th grade.
How do the 12- and 24-hour clocks relate to other areas of math?
Children are sometimes required to read and interpret timetables (such as timings of a school day, or a bus timetable) which will often use timings either written in the 12- or 24-hour clock.
